Facile One-Step Dynamic Hydrothermal Synthesis of Spinel LiMn2O4/Carbon Nanotubes Composite as Cathode Material for Lithium-Ion Batteries

Nano-sized spinel LiMn2O4/carbon nanotubes (LMO/CNTs) composite is facilely synthesized via a one-step dynamic hydrothermal approach. The characterizations and electrochemical measurements reveal that LiMn2O4 particles with narrow size distribution are well dispersed with CNTs in the composite. The LMO/CNTs nanocomposite with 5 wt % CNTs displays a high specific discharge capacity of 114 mAh g-1 at 1C rate, and the retention rate after 180 cycles at room temperature reaches 94.5% in the potential window of 3.3 to 4.3 V vs. Li/Li+. Furthermore, the electrochemical performance of the composite with 5 wt % CNTs at elevated temperature (55 °C) is also impressive, 90% discharging capacity could be maintained after 100 cycles at 1C. Such excellent electrochemical performance of the final product is attributed to the content of CNTs added in the hydrothermal process and small particle size inherited from pretreated MnO2 precursor.

Size Induced Structural Changes in Molybdenum Oxide Nanoparticles

Nanosizing of metal oxide particles is a common strategy for improving materials properties; however, small particles often take structures different from the bulk material. MoO₂ nanoparticles show a structure that is distinct from the bulk distorted rutile structure and which has not yet been determined. Here, we present a model for nanostructured MoO₂ obtained through detailed atomic pair distribution function analysis combined with high-resolution electron microscopy. Defects occur in the arrangement of [MoO₆] octahedra, in both large (40-100 nm) nanoparticles, where the overall distorted rutile structure is preserved, and in small nanoparticles (<5 nm), where a new nanostructure is formed. The study provides a piece in the puzzle of understanding the structure/properties relationship of molybdenum oxides and further our understanding of the origin of structural changes taking place upon nanosizing in oxide materials.

Structural stability and thermoelectric properties of cation- and anion-doped Mg2Si0.4Sn0.6

The structural stability of undoped and doped (Sb, Bi, Ca, Zn) Mg₂Si_0.4Sn_0.6 is investigated by high resolution synchrotron PXRD and related to measured physical properties, revealing a stabilizing effect of cation doping.

High-performance carbon-coated mesoporous LiMn2O4 cathode materials synthesized from a novel hydrated layered-spinel lithium manganate composite

High-performance carbon-coated mesoporous LiMn₂O₄ cathode materials have been synthesized from a novel hydrated layered-spinel lithium manganate composite.